Background: Community-acquired pneumonia (CAP) is a major cause of morbidity and mortality among children. S100A12 is suggestive to be a useful marker for diagnosis and severity assessment of CAP. We sought to assess the serum level of S100A12 in children with complicated and noncomplicated CAP and its correlation to CAP severity and prognosis. Methods: In this controlled cross-sectional study, we measured serum levels of S100A12 using enzyme linked immunosorbent assay in 30 patients with complicated CAP, 30 patients with noncomplicated CAP and 30 healthy children. CAP severity was assessed using British Thoracic Society (BTS) criteria. Serum S100A12 levels, serum C- Reactive Protein (CRP), and serum procalcitonin (PCT) concentrations were quantified. Radiological assessment included chest x ray, lung ultrasound, and Computed Tomography (CT) scans. Results: Serum S100A12 levels were significantly higher in CAP patients (median 451.22 ng/mL) than in controls (median 112.65 ng/mL). Complicated CAP cases had higher S100A12 levels (587.92 ng/mL) than noncomplicated cases (330.11 ng/mL). A cutoff value of >410.23 ng/mL predicted complicated CAP with 83.33% sensitivity and 70.00% specificity. S100A12 levels were also significantly elevated in severe CAP cases. Conclusions: Serum S100A12 is a promising biomarker for CAP severity assessment. Higher levels are associated with complicated CAP and may help predict disease severity and prognosis in affected children.